In recording apparatuses of the type shown in U.S. Pat. Nos. 3,373,437 to Sweet et al and 3,618,858 to Culp, a plurality of liquid streams is supplied under pressure. Each of the streams passes through a separate charging electrode where each of the droplets, which is formed from the stream within the charging electrode, is either charged or not charged so as to determine whether the droplet will strike a recording medium such as paper, for example.
To control each of the charging electrodes, it is necessary to use a separate wire from a source of power to each of the electrodes. Thus, with fifty to one hundred charging electrodes in a charging electrode array, for example, the number of wires become excessive.
Additionally, because of the relatively small size of the passage through which the liquid stream and the droplets formed therefrom are passing, it has been difficult to plate the surface of the passage, for example. This plating is necessary to produce the charging electrode.
The present invention satisfactorily solves the foregoing problems by providing a control head in which the number of wires required to the power source is reduced by one or two orders of magnitude. Furthermore, the present invention also overcomes the difficulty of forming the charging electrode.
The present invention accomplishes the foregoing through utilizing a semiconductor substrate and forming each of the charging electrodes by a diffusion into at least a selected portion of each passage in an array of passages in the substrate. Additionally, each of these diffusions is connected through a latch circuit, which can be formed in the front surface of the substrate, to a shift register, which also can be formed in the front surface of the substrate. The connection from each of the diffusions, which form the charging electrodes, to the latch circuit is by a diffused region.
Accordingly, the present invention requires only two wires to the shift register to supply the information to all of the charging electrodes with one wire supplying the data and the other wire supplying pulses to shift the data, a single wire to the latch circuits to activate them to allow the signals in the shift register to be supplied to the diffused regions, and a single wire supplying power to both the latch circuits and the shift register. Thus, the shift register allows power to be supplied through the latch circuit to each of the charging electrodes or prevents it in accordance with the data signal at the shift register for the particular charging electrode.
An object of this invention is to provide a unique control head for controlling the charging of liquid droplets to be used in a recording apparatus.
Another object of this invention is to provide a recording apparatus having charging electrodes for charging the droplets and the control circuits for the charging electrodes in a single element.
The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention as illustrated in the accompanying drawings.